Downey, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30.8 °F (low) to 59 °F (high). Annual precipitation averages 13.1 Inches. Downey is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.2 °F | 32.6 °F | 1.08 in. |
| February | 16.4 °F | 37.0 °F | 0.95 in. |
| March | 24.3 °F | 47.5 °F | 1.48 in. |
| April | 30.0 °F | 56.5 °F | 1.36 in. |
| May | 37.2 °F | 66.3 °F | 1.62 in. |
| June | 43.1 °F | 76.9 °F | 0.83 in. |
| July | 49.8 °F | 88.4 °F | 0.76 in. |
| August | 48.4 °F | 86.7 °F | 0.85 in. |
| September | 39.8 °F | 76.0 °F | 1.35 in. |
| October | 30.8 °F | 60.9 °F | 1.18 in. |
| November | 22.1 °F | 45.4 °F | 0.89 in. |
| December | 15.0 °F | 34.0 °F | 0.79 in. |
| Annual | 30.8 °F | 59 °F | 13.14 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |